1. Field of the Invention
The present invention relates to a database management program, a database management apparatus and a database management method for managing a database for profile data.
2. Description of the Related Art
Product development in the manufacturing industries does not necessarily mean design activities involving new preparations of elements of three-dimensional shape models and two-dimensional drawings. All or part of the data of existing three-dimensional shape models and two-dimensional drawings are more often than not copied and reused to shorten the work period and reduce the cost. For this reason, the elements of the three-dimensional shape models and the two-dimensional drawings that are utilized frequently are stored in a DB (database) that is referred to as “model L (library) DB (database) as unit models (including standard models and common models) to be reutilized. With such an arrangement, the designer can design a new product by exploiting the existing assets, taking out data from the model LDB for use whenever necessary.
In the operation of exploiting the existing assets, it can be time consuming to retrieve the model that the designer wants from such an LDB, or a database storing existing models. Reduction of the time to be spent for retrieving the model that the designer wants results in reduction of the entire product design period and cost down for the development of the new product. Such an LDB may be exploited not only when the designer retrieves the model he or she wants for designing a new profile. When one of the existing models is altered, the models that relate to the altered model may have to be retrieved and, if necessary, modified. The models that relate to the altered model may include those that are entirely or partly being exploited by the designer. Additionally, if any of the models in the product that is shipped and marketed is found to be in need of improvement, it may be necessary not only to modify the model but also to retrieve all the products produced by utilizing the model and replace it with a faultless model. Thus, there are many scenes where one or more than one models and/or one or more than one profiles need to be retrieved in any of the processes in the life cycle of a product, including the stages of preparation, design, manufacturing, shipment and disposal. Therefore, there is a strong demand for techniques that allow a quicker access to necessary data by reducing both the time for retrieving data and the time for collecting pieces of information.
Now, known techniques for retrieving a model will be discussed below. Such techniques include firstly “character string retrieval techniques” that give meaningful titles to the models and the drawings that may be exploited in the future and store the models and the drawings in advance so that necessary data may be retrieved by means of a command on a CAD (Computer Aided Design) system or a data management system, using a character string found in some of the titles of the models and the drawings as retrieval key. However, many CAD systems are so designed that necessary data can be retrieved not by using a character string but by using as retrieval key a piece of attribute information that a model or a drawing has, which may be color information on the color put to an element of the model or the drawing such as “red” or “blue” or material information such as “iron” or “aluminum”. As for two-dimensional drawings, there are CAD systems where the drawing that a designer needs can be retrieved by using as retrieval key the type and the number of elements contained in the drawing such as line segments or circles. There are various pieces of information that characterize three-dimensional models including the numbers of components such as colors, shapes, volumes, areas, surfaces and edge lines, shape lines, moments of inertia and aspect ratios. Thus, there are CAD systems where the model that a designer needs can be retrieved by using as retrieval key one or more than one of such characteristics.
Researches are being made in various technical fields for “shape matching” of detecting a model having a profile that resembles the shape of the model of a retrieval key not by using a characteristic string or a piece of attribute information but by using a whole three-dimensional shape. Processing techniques that processes images for “matching” have also been devised. For example, known such techniques include those that convert a two-dimensional drawing into image data in order to judge the similarity of shape according to the degree of similarity of parts where lines are involved and those that convert the state of a three-dimensional image being displayed on a display screen into image data and evaluate the degree of undulations produced due to the degrees of luminance of contour profiles and surfaces in order to judge the similarity of shapes.
In the current situation where three-dimensional CAD system have become popular and taken a major role to replace two-dimensional CAD systems, it is indispensable to retrieve a three-dimensional model that agrees with the profile that the designer wants from the viewpoint of marketing the product early and reducing the product development cost for the purpose of achieving a high turnover. Therefore, there is a strong demand for functions and tools for such retrieval operations. As a matter of fact, similar shapes retrieval engines for retrieving three-dimensional CAD data have been provided (see, for example, Non-Patent Document 1: Mutoh Industries, Ltd., “3DSearchIT”, URL=http://www.mutoh.co.jp/it/products/3dsearchit/index.htm, Jul. 29, 2002, Non-Patent Document 2: IBM Japan IBM, Ltd., Tokyo Research Laboratory, “Three-Dimensional Shape Similarity Retrieval Technology”, URL=http://www.research.ibm.com/trl/projects/3dweb/SimSearch.htm, Sep. 30, 1999.
The conventional art that relates to the present invention includes design support apparatus that can present combinations of exemplary parts and standard parts necessary for designs for realizing required specifications and facilitate the operation of building a standard part database (see, for example, Patent Document 1: Jpn. Pat. Appln. Laid-Open Publication No. 9-179892).
While similar shapes retrieval engines designed so as to be incorporated in CAD systems are known as pointed out above, they are simply tools for retrieving similar shapes. However, in actual design scenes where a CAD system is being exploited, designers have mostly specific numerical values such as those of lengths and angles in mind. For example, a designer may wants a model that snugly satisfies certain requirements as expressed by “a product model having three 10 mm holes”. Then, it is necessary not only to retrieve similar profiles but also to narrow down the candidate models to a model or models that meet the requirements.
Furthermore, when models are retrieved by means of attribute information such as color information and contour line information, they are downloaded from a DB and attribute information on a shape is taken out from a memory and compared with a retrieval key. Then, the retrieval process will be very time consuming because it involves not only the proper model retrieving operation but also the process time necessary for loading the retrieved models in the system and releasing the memory.